import thenFs from "then-fs";
thenFs.readFile('111.txt', 'utf-8').then((r1) => {
        console.log(r1);
        return thenFs.readFile('222.txt', 'utf-8')
    })
    .then((r2) => {
        console.log(r2);
        return thenFs.readFile('333.txt', 'utf-8')
    })
    .then((r3) => {
        console.log(r3);
    }).catch((err) => {
        console.log(err.message);
    })